In an architecture where bearer and control are separated, a gateway control protocol, for example, H.248, is usually adopted as a control protocol between a service layer control entity and a media plane execution entity. In this mechanism, the media plane execution entity includes a media gateway (Media Gateway, MG), and the service layer control entity includes a media gateway controller (Media Gateway Controller, MGC).
With wide application of an IP service, a security issue of data transmission on a network becomes more and more important. It can be seen from the perspective of a protocol that, security of the IP service mainly includes two aspects: One is security of a control plane and the other is security of a media plane.
The real-time transport protocol (Real-Time Transport Protocol, RTP), formulated by the Internet Engineering Task Force (Internet Engineering Task Force, IETF), is a protocol designed for multimedia data stream transmission. The RTP is responsible for multimedia data transmission, while the real-time transport control protocol (RTP Control Protocol, RTCP) provides functions such as quality of service monitoring, congestion control and media synchronization. The RTP provides a certain degree of confidentiality, and may encrypt an RTP payload. However, a default algorithm of the RTP is easy to be cracked. The IETF extends the RTP protocol, and puts forward the Secure Real-Time Transport Protocol (Secure Real-time Transport Protocol, SRTP). Usually, SRTP key information used in a session is negotiated through the Session Initialization Protocol (Session Initiation Protocol, SIP), and key information is transmitted through interaction between the service layer control entity and the media plane execution entity. In this way, a security function of the media plane is implemented.
In a current network scenario, although receiving and using a media stream transmission key are supported at service and bearer layers, an operation cannot be performed on a lifetime status of the media stream transmission key.